Modern electronics devices, such as integrated circuits ("ICs") or semiconductor "chips" are rapidly increasing in production quantity and functionality, while decreasing in size and unit cost. For increasing productivity of the electronic devices, it is required to decrease test cost and test time. This can best be accomplished with fully automated electronic device test systems.
In a conventional test system, electronic devices to be tested are removed from their container, usually called a "magazine," and separated from one another by the force of gravity. That is, the electronic device to be tested is positioned initially at a vertically higher position than the test head and, by its own weight, is separated from the other devices such that it slidably descends to the test head. After the test, the electronic device descends further, due to gravity, to a lower position than the test head so as to be sorted depending on the test results.
Such conventional device test systems, which utilize the force of gravity to separate and transfer the electronic devices, have two inherent disadvantages. First, since modern electronic devices have become smaller and lighter than before, an individual electronic device does not have sufficient weight to efficiently separate from the others. This causes "jamming," wherein two or more electronic devices stick together and cannot separate from one another. If such jamming occurs, it is usually necessary to stop the operation of the test system to clear the jam, thus causing a serious loss of time and efficiency. Furthermore, the risk of jamming is greatly increased due to the configuration of the new types of electronic devices to be tested. For example, one new type of electronic device has electric leads (pins), not only on two sides of the chip package (as in the conventional dual-in-line or "DIP" package), but on all sides of the package.
Second, to avoid further jamming, the outer surface of the electronic device must be made sufficiently smooth so as to not cause any friction or unwanted engagement with other devices. However, this is also impractical since the plastic molded packages of the devices inevitably have some burrs remaining from the production process. It is not economically practical to completely eliminate such burrs. Therefore, the electronic device test systems which rely on the force of gravity for device separation and transfer suffer from a few serious disadvantages in view of modern techniques in electronic device packaging.
Therefore, there is a new type of test handler which intends to overcome such disadvantages inherent to conventional types of test handlers. The improved test handler increases manufacturing productivity of such electronic devices, and thereby reduces their unit cost, by increasing the test speed by testing a plurality of the devices at the same time.
The new type of automatic test handler places a number of electronic devices to be tested on a test tray and positions them so as to be engaged by a test head plate having a number of corresponding test contactors. One device is placed on a seat of a carrier module, and each carrier module is provided with one or two device seats. A number of modules are then arrayed by column and row in a test tray. The test tray having a number of carrier modules is arranged so as to be in vertical alignment (either above or below) with a test fixture. The test fixture includes test contactors (test pins) for contact with pins of the device to be tested for supplying test signals and receiving the response signals from the device. Each module is aligned with a corresponding test contactor so that when either the test tray or the test fixture are moved vertically toward another, the contactor engages the electronic device positioned within the carrier module.
The contactor is provided with a number of test pins or electric leads which come into electrical communication with the leads of the electronic devices to be tested. The automatic test handler is electrically connected to a electronic device test system, for example, an IC tester which includes a test signal generator for supplying a test signal to the device, and with a signal comparator for analyzing the results of the test. Based on such results, the electronic devices are transferred to another location in the test process and sorted for proper handling.
Even in such an automatic tester, there is a need to take out electronic devices to be tested from a container and place the devices in an appropriate position on the test tray before the test. It is also necessary, after the test, to take out the tested devices from the test tray and sort them, based on the test results, into containers for shipping. Because of the recent demands in the electronics industry, as stated above, various new devices having new types of packaging have been developed. Containers for such new devices are also changing. One of the examples of such a container is called "a customer tray" wherein a number of devices are aligned in a horizontal plane, similar to the test tray as described above.
However, the customer trays are different in size, shape, capacity and spacing between the seats of the devices from manufacturer to manufacturer. The spacing in the customer tray is also different from the spacing in the test tray since the test tray requires more accuracy for securing the perfect contact with the test contactor and the device leads. Therefore, it is also necessary in the new type of test handler to equip a pick and place apparatus with the capability to adjust distances between the devices to overcome the differences in the spacing of the devices in the customer trays.
Thus, there is a need in the electronic device test industry for a pick and place which can pick the devices and place them in the test tray, while adjusting a space difference between the devices in the trays, and subsequently pick up the tested devices and sort them in accordance with the test result into the customer trays for shipping.